Colombia's heavy oil area could hold 20bn barrels of recoverable resources,giving the country greater reserves than leading producers such as Mexicoand Algeria, said its natural resources agency.

Foreign investment in Colombia's oil and gas industry is booming, and thecountry hopes to lift oil production to 1m barrels a day in the next decade,from about 550,000 b/d currently.

Colombia's heavy oil potential is dwarfed by that of its neighbourVenezuela, which is estimated to have at least 240bn barrels recoverable inits Orinoco belt region. But Colombia has the great advantage of welcomingforeign investment.

It is one of the few countries with significant resources becoming moreaccessible to international companies, and capable of growth in oil exports.

The ANH, Colombia's national hydrocarbons agency, is on Wednesday settingout details of Colombia's second licensing round in London, followingpresentations in Houston last week.

Halliburton also suggested Colombia could have more than 50,000bn cubic feetof gas, about as much as Canada or the Netherlands.

David Thomson of Wood Mackenzie, the consultancy, said he thought theestimate of recoverable heavy oil was "probably on the hopeful side, but byno means impossible".

"Colombia is not like Venezuela, Bolivia or Ecuador, which have all beenpursuing unfriendly policies towards business, and its geology is alsorelatively easy, so it is attractive."

Armando Zamora, director-general of the ANH, told the Financial Times hethought Colombia was now the most popular country in Latin America forforeign investment in oil and gas production. That investment rose from$1.8bn in 2006 to $3.5bn last year, and is expected to be close to $5bn(€3.2bn, £2.5bn) this year.

Mr Zamora acknowledged that in the areas being offered for heavy oil therewere security concerns because of possible attacks by Farc rebels, which hesaid took refuge in bases across the border in Venezuela, and there would bea need for the government to deploy additional troops "to be on the safeside".

However, Farc activity had declined sharply.

He would reassure potential investors about the tension between Colombia andits neighbours Venezuela and Ecuador. "There is no chance we would start awar with them," he said.